Wells Fargo's fake accounts scandal expanded Thursday with the disclosure of roughly 1.4 million more potentially unauthorized accounts than the bank originally estimated when the embarrassing episode emerged nearly a year ago.

The announcement confirmed Wells Fargo CEO Tim Sloan's Aug. 22 forecast that the investigation likely would confirm wider consumer damage from the scandal by disclosing a new detail: unauthorized enrollment of customers in the bank's online bill payment system.

While the new disclosures concluded the bank's review of the issue, investigations or reviews of the episode by the Department of Justice, the Securities and Exchange Commission, the Federal Reserve and other authorities are continuing.

The San Francisco-based bank initially reviewed 93.5 million current and former customer accounts opened from May 2011 through mid-2015 and identified roughly 2.1 million potentially unauthorized accounts.

But Wells Fargo said the newly completed independent review, which examined more than 165 million retail banking accounts opened from Jan. 2009 through Sept. 2016, found approximately 3.5 million potentially unauthorized accounts.

In all, consumer and small business owners of approximately 190,000 accounts incurred Wells Fargo fees and charges, up from roughly 130,000 accounts previously identified. The bank said it would provide a total of $2.8 million in new refunds and credits beyond the $3.3 million previously refunded.

The expanded review also examined online bill payment services and found approximately 528,000 potentially unauthorized enrollments. Wells Fargo said it would refund $910,000 to customers who incurred fees or charges in connection with the services.

"We apologize to everyone who was harmed by unacceptable sales practices that occurred in our retail bank," Sloan said in a statement issued with the disclosure. "To rebuild trust and to build a better Wells Fargo, our first priority is to make things right for our customers, and the completion of this expanded third-party analysis is an important milestone."

The news sent Wells Fargo shares down 29 cents to a $51.07 close in Thursday trading.

Evercore ISI financial analysts John Pancari, Samuel Ross and Rahul Patil in a Thursday note to investors said details of the expanded scandal likely would weigh on Wells Fargo's shares. But the analysts maintained an outperform rating on the stock, pending any additional disclosures by investigators.

The scandal came to national attention in Sept. 2016 when the bank was hit with $185 million in penalties by the Consumer Financial Protection Bureau, the Office of the Comptroller of the Currency and Los Angeles legal officials for secretly opening unauthorized deposit and credit-card accounts that harmed customers.

An investigation conducted by the authorities found Wells Fargo employees improperly boosted the bank's sales figures by covertly opening the accounts and funding them by transferring money from customers' authorized accounts without the owners' knowledge or permission.

The secret practice stemmed from Wells Fargo incentive programs that linked bank employees' income to the number and volume of new accounts opened.

A civil action filed by the federal and state investigators charged that Wells Fargo Bank and its parent, Wells Fargo & Co., "victimized their customers by using pernicious and often illegal sales tactics to maintain high levels of sales of their banking and financial products."

The bank belatedly confirmed that it had terminated approximately 5,300 employees and managers over a five-year period for their involvement with the unauthorized accounts. The firings represented roughly 1% of the total workforce during that time frame.

Many of those workers contended that bank supervisors had pressured them to open ever-increasing numbers of accounts as part of Wells Fargo retail sales drives.

Wells Fargo agreed to a civil settlement with the federal and state authorities as its reputation for regularly topping bank competitors with the number of accounts held by customers suddenly boomeranged into a damaging liability.

Then-Wells Fargo chief executive John Stumpf announced his retirement as the accounts scandal prompted withering criticism from consumer advocates and Congress.

In response, Wells Fargo overhauled its pay system and incentive goals, ousted several executives and clawed back tens of millions of dollars in compensation from Stumpf and another former executive.

Beyond the refunds prompted by the new review, the bank said it has provided more than $3.7 million in refunds and credits to customers for complaints and mediation claims from Sept. 8, 2016, through July 31, 2017.

Bank customers whose credit scores were affected by the accounts scandal also may receive compensation under a recent $142 million class-action lawsuit settlement for claims that date back to 2002.

Most recently, Wells Fargo shook up its board of directors in an effort to increase independent review of the bank's operations.

Former Federal Reserve governor Elizabeth "Betsy" Duke, the board's current vice chairperson, will take the top job Jan. 1. Duke will become the first woman to hold the chairperson role at one of the nation's largest banks,

Wells Fargo, which had previously added two independent directors, also said it expected to name three additional independent board members before the bank's 2018 annual meeting.

Nonetheless, Wells Fargo, the nation's largest mortgage lender and third-largest bank by assets, has suffered other hits to its reputation in the months since the scandal surfaced.

The bank disclosed in July that it would make $80 million in payments to more than 570,000 auto loan customers who also were charged for auto insurance without their knowledge.

A federal lawsuit filed this week accused the bank of systematically charging mortgage borrowers fees to extend locked-in interest rates when closings on the loans were delayed. Wells Fargo declined to comment on the legal complaint.

The bank said it would continue efforts to rebuild customer trust by helping present and former account holders get information and compensation from the class-action settlement.

Wells Fargo also plans to contact all customers who complained about unauthorized accounts opened in their names and will offer mediation if the company is unable to resolve the issues.